1. Field of the Invention
The present invention relates to a technology for conveying waste toner.
2. Description of the Related Art
In some electrophotographic systems for forming images, waste toner after a toner supplying process or an image forming process is conveyed by a conveyor belt. In one conventional technique, while a driving shaft is rotating, a projection provided at the driving shaft fits in one of holes arranged in a center line of the conveyor belt to apply a driving force to the conveyor belt. In another conventional technique, a pinion gear is meshed with the conveyor belt to apply a driving force to the conveyor belt. However, it frequently happens that the conveyor belt is inclined to one side due to poor fitting between the hole and the projection of the driving shaft, poor fitting of the pinion gear, and uneven tension of the conveyor belt, resulting in unstable running of the conveyor belt.
Japanese Patent No. 3281595 discloses an electrophotographic recording apparatus that includes a cleaning unit, a toner housing chamber, and a waste-toner conveyor belt. Waste toner that is removed from a photoconductor is conveyed to the toner housing chamber by the conveyor belt sliding and running along a groove. In the electrophotographic recording apparatus, the groove is used only for conveying the waste toner, and the conveyor belt cannot maintain the stable running due to the poor fitting of the driving shaft, the uneven tension of the conveyor belt, or the like.
Japanese Patent No. 3327380 discloses an image forming apparatus in which an inlet for waste toner is arranged higher than a lower cyclic axis of a conveyor belt, and a driving source is linked to the conveyor belt at an upper cyclic axis side to apply a driving force to the conveyor belt. Specifically, a pinion gear is meshed with the conveyor belt to apply the driving force to the conveyor belt. Accordingly, it frequently happens that the conveyor belt is inclined to one side due to the poor fitting of the pinion gear, and the uneven tension of the conveyor belt. As a result, the stable running of the conveyor belt cannot be maintained.
Japanese Patent No. 3244972 discloses a toner housing device in which a conveyor belt for conveying waste toner has long holes, and a driving roller for driving the conveyor belt has a projection that fits in one of the long holes to apply a driving force to the conveyor belt. That is, the projection of the driving roller fits in one of the holes arranged at the center of the conveyor belt such that the conveyor belt is driven with the rotation of the driving roller. Although a stress on the toner is mitigated, it frequently happens that the conveyor belt is inclined to one side due to the poor fitting between the hole of the conveyor belt and the projection of the driving roller, and the uneven tension of the conveyor belt. As a result, the stable running of the conveyor belt cannot be maintained.
Japanese Patent Application Laid-Open No. H8-6372 discloses a toner supplying unit that includes a conveyor belt mechanism including an endless conveyor belt that conveys toner with holding the toner therein, a flat toner hopper that houses the toner and has a toner supplying outlet at a toner supplying roller side, and a driving mortar that drives the conveyor belt mechanism. The conveyor belt has a plurality of holes from which the toner is supplied, and extends around pulleys. The pulleys at the toner supplying roller side support at least both sides of the conveyor belt. In the toner supplying unit, because a roller is meshed with one of the holes of the conveyor belt to drive the conveyor belt, it is difficult to remove the powdery material with which the hole is clogged. As a result, the stable running of the conveyor belt cannot be maintained. The holes and a space for conveying the powdery material can be separated by a separator such as a partition. However, such a structure increases the number of required members, which makes the toner supplying unit complicated. Moreover, when a fine powdery material such as a toner is used, the powdery material cannot perfectly separated by the partition. In other words, it is difficult to prevent the holes to be clogged.